It has been known since the 1950s that infectious diseases of poultry such as infectious Corzya of chickens or Fowl Cholera of chickens or turkeys are caused by specific bacterial species. Infections Corzya is caused by the organism Hemophilus gallinarum (paragallinarum) and Fowl Cholera is caused by Pasterurella multocida.
It has also been known for some time that there are a number of different serotypes of these bacteria each of which is capable of causing nearly identical disease syndromes. Birds which have been infected naturally or artifically, i.e. by innoculation, with one serotype will, upon recovery, be resistant to disease if exposed to different serotypes of the same bacterial species. For instance, if a chicken is infected with Hemophilus gallinarum serotype A and following recovery is exposed to serotypes B or C it will be resistant to the second exposure. Similarly if a chicken or turkey has been exposed to Pasterurella multocida, Type 1, and recovers from the disease it will be resistant to subsequent exposure to types 3, 4, etc. This, of course, presumes that the bird survives the first onset of the disease.
For many years killed cultures of these bacteria (bacterins), which had been grown on various artificial media, have been used to attempt to prevent the disease caused by these organisms. Unfortunately, however, contrary results have arisen. Thus if a chicken is vaccinated with a bacterin prepared from Hemophilus gellinarum serotype A it will not be protected against exposure to serotypes B or C. Similarly fowl cholera bacterins prepared from type 1 Pasteurella multocida will not protect birds exposed to other types of Pasteurella.
It has been shown that bacterins prepared from organs such as livers that have been removed from turkeys that died of fowl cholera can be used to prepare a bacterin which is capable of protecting turkeys that have been vaccinated with this bacterin against exposure to heterologous types of Pasteurella multocide bacteria.
While such a finding is of academic interest it is not a practical procedure for commercial production of a bacterin.